What is the main conflict in A Summer to Die by Lois Lowry?

A Summer to Die by Lois Lowry tells the story of thirteen-year-old Meg Chalmers whose whole life is turned upside down when her parents, Charles and Lydia Chalmers, tell her and her fifteen-year-old sister, Molly, that they will be closing up their family home in the small New England town where they live and moving to a country farmhouse. The girls are shocked. Molly's illness is also a conflict.